Gimurei

ギムレー, Grima,Evil Dragon (邪竜),Fell Dragon,The Creation (造られしもの),Hierophant

Grima is the true main antagonist in Fire Emblem Awakening, and a secret boss in Fire Emblem Echoes: Shadows of Valentia. Grima tends to go by the title of the Fell Dragon and is feared by most of the world.

(Source: Fire Emblem Wikia)